Consider a normal distribution curve ...

Question

Consider a normal distribution curve where the middle 30 % of the area under the curve lies above the interval ( 7 , 15 ). Use this information to find the mean, (μ) , and the standard deviation, (σ) , of the distribution.

MEAN = _____

STANDARD DISTRIBUTION = ___

Answer 1

mean is the average = (15+7)/2= 22/2 = 11

z score = .385 = (15-11)/sd for 30% under the graph

use a z score calculator

sd = 4/.385 = about 10.9 = standard deviation